NASA/JPL/Space Science Institute A huge arrow-shaped storm blows across the equatorial region of Titan in this image from NASA's Cassini spacecraft, chronicling the seasonal weather changes on Saturn's largest moon.

He shifted his hand from her head to her shoulder and dug his nails in hard, causing her to wince and look him in the face, her eyes drawn to the arrow-shaped decay in his upper lip, and the virulence of its infection.